Hydroplane boat hull



June 17, 1969 c, VAN PATTEN 3,450,085

HYDROPLANE BOAT HULL Filed May 10, 1967 INVENTOR v Char/es Doug/as VanPatten ATTORNEY United States Patent O 3,450,085 HYDROPLANE BOAT HULLCharles Douglas Van Patten, Carp Lake, Mich., assignor to StanrayCorporation, Chicago, Ill., a corporation of Delaware Filed May 10,1967, Ser. No. 637,596 Int. Cl. B63b 1/18 U.S. Cl. 114-665 ClaimsABSTRACT OF THE DISCLOSURE BACKGROUND OF INVENTION Field of theinvention The invention pertains to hydroplane boat hulls, whether forpleasure, commercial, or military use.

Description of the prior art Certain previously patented inventionsembody some of the elements of applicants invention. For example, therelatively sharp outboard edges and aftwardly converging relationship ofthe separators on the hull bottom are shown by Eddy Patent No.1,935,622, Eddy and Van Patten Patents Nos. 2,039,585 and 2,039,586, andby Van Patten, applicant herein, Patent No. 2,423,860, but in no priorpatent known to applicant is the transversely horizontal side of thesubstantially triangular-in-section separators shown wherein theseparators are splayed in complementary relationship to the hulls planeof symmetry and converging toward the after end of the hull, with theoutboard edges of such separators as sharp as practical to provide aflow separator.

SUMMARY OF THE INVENTION The present invention uses thetriangular-section element on the hull bottom primarily as a flowseparator and only secondarily as a pressure distribution adjuster.Furthermore, in the present invention the pressure distribution isadjusted principally for controlling the longitudinal, rather than thetransverse, trim of the hull at planing speeds. This form of boatpossesses inherent transverse dynamic stability which is a result of theflow separation function of the triangular-section elements. Theseparators are preferably used on a hard-chine hull having convextransverse sections, polyparaboloidal and oriented outboard andcomplementary about a longitudinal and vertical plane of symmetry,although it will be understood that these separator devices could beadapted for application to or embodiment in other forms of hulls such asthose having round bilges, concave transverse sections, etc.

BRIEF DESCRIPTION OF THE DRAWING of FIG. 1, slightly 3,45%,085 PatentedJune 17, 1969 The invention comprises the application to or integralformation with a polyparaboloid hull form of edge effect devices whichare triangular in cross section, and applied to the boat bottom, anequal number on opposite sides of the plane of symmetry, each at anangle thereto. This angle is important as any variation in theangularity of each device with respect to the plane of symmetry makes adifference in effect. Theoretically, the best results would be had byarranging the angles of the edge elfect devices so that the riser edgescome as close as possible to a right angle with the line of Water at anypoint Without interfering with atmospheric access to the downstream sideof said devices, especially at low and medium speeds, with a consequentreduction of flow separation and a fatter drag curve.

From a practical standpoint, the angles that the edge effect devicesmake with the plane of symmetry, or with the lines of water flow, are acompromise such as will initiate flow separation relatively low in thespeed range and at the same time produce relatively massive flowseparation in the upper part of the speed range.

Viewed in plan, the angle of the separator edge with the hulls plane ofsymmetry may range from a minimum of 1 to a maximum of 69. This anglepreferably increases with each aftwardly succeeding complementary pairof separators. This successive increase may be of a constant rate or ofan increasing or decreasing rate.

Viewed in plan, the separator riser edges may be straight or curvedlines. If they are curved, the splay angle mentioned above would be thatmeasured between the plane of symmetry and a chord intersecting the endsof the separator riser or that measured between the plane of symmetryand corresponding tangents to the riser edge.

The basic hull form required for the logical application of the edgeeffect devices of my invention is a very special one. Theoretically,this hull form may be referred to as a polyparaboloid shape, and issomewhat like a conventional high dead-rise deep V hull. My new hullform differs from the deep V form in having a distinctly sharpergarboard region, and in the elimination of the straight sectioned,substantially flat chine area of the bottom in favor of a definitelyconvex parabolic configuration. These differences are markedlynoticeable in riding comfort and sea-keeping abilities. The deep V shapetends to pound severely in quartering seas, on or off the wind, whereasthe polyparaboloid form is relatively soft riding on any heading withrespect to sea and wind.

Both the polyparaboloid and the deep V forms are drier running, i.e.,take less spray aboard, are softer riding, and are more seaworthy thanthe current cathedral form of rectangular boat. The cathedral hull takesannoying spray aboard because of its excessive length of submergedchine. The spray comes olf the chines far forward and at relatively lowvelocity. Appreciable wind on the beam tends to fling this spray aboard,annoying the passengers. In contrast, the polyparaboloid hull, as wellas the deep V hull is comparatively dry-running because the spray leavesthe chines farther aft, at relatively high velocity, and at a low angle.By the time the Wind can pick up this spray, the boat is long gone, andthe spray falls harmlessly in its wake.

In the drawings, the novel form of hull is shown at 10 and as beforestated this hull can be defined as a hard chine hull having convextransverse sections, paraboloidal and oriented outboard, andcomplementary about a longitudinal and vertical plane of symmetryindicated by the line 11-11, FIG. 3. To the bottom of this basic hullform are subimposed a complementary pair, or pairs, of substantiallytriangular-section separators or steps 12,

3 which extend from substantially the chine 14 of the hull,progressively increasing in width, and converge aftward as clearly shownin FIG. 3. The separators are preferably molded integrally with thehull, although they could be provided separately and applied to a hullwith a good strong tension type of marine glue. As shown in FIG. 4, thebottom surfaces 16 of these separators are substantially horizontaltransversely throughout their length, except for a short portion oftheir forward ends where it is necessary or convenient to fair them intothe basic hull surface or the chines 14. The riser surfaces 18 of theseseparators 12 face outwardly and aft and are substantially vertical withsaid bottom surfaces, and the intersection of said bottom and risersurfaces is as sharp as may be structurally practical.

While the foregoing hull form is preferred for the application of myimproved separator devices, they may be applied with beneficial effectto hulls of other basic form, such as those having round bilges,concave, convex or sigmoidal transverse sections, and the like.

Also they may be applied with advantage to hydroplane hulls of the formhaving substantially transverse steps which divide them into a forebodyand an afterbody, and in some cases one or more middle-bodies.

The substantially transversely horizontal surface of these separators 16have a varying transverse dimension if the riser height is maintainedconstant with a varying hull deadrise. They will also have a varyingriser height if the transverse dimension is held constant with the saidvarying hull deadrise.

A geometric definition of a practical range of this riser height forhydrop-lane hulls may be expressed as follows:

(non-dimensional) where H=Riser height A=Gross displacement (weight) ofvessel B=Maxirnum breadth between chines V=Speed of advance K=Riserheight coefficient And, where:

H=Inches A=Pounds B=Inches V=Knots Then: The value of K, for practicalhulls of this form, lies between 0.0660 and 0.8050, with the requirementin the case of relatively sharp (small radius) separator edges beingtoward the smaller value, and the requirement in the case oflarge-radius separator edges being toward the greater value.

However, the functioning of such a separator device requires atmosphericaccess to the region immediately downstream of the raiser surface, andthis is sensitive to the riser height. Thus it is considered mostpractical to employ an adequate minimum riser height for each separatorand to maintain this constant, except for the short faired portion atthe forward end, as set forth above. As a. geometric and structuralpracticality, a fillet of minimum radius is used as at 20 at theintersection of the riser surface 18 with the basic hull surface. Forhydrodynamic and structural reasons, a fillet of relatively large radiusis used as at 22 at the intersection of the separator bottom surface 16with the basic hull surface.

It will be noted that the most forward pair of separator devices 18-48are the longest, they are the narrowest at their forward end,progressively widen in plan view toward their after end, and are locatedapproximately midship of the overall boat length. In relation to theplane of symmetry 11-11 they converge aft theretoward at the leastangle, and are the closest to said plane.

The most rearward pair of the separator devices are the shortest, theyare the farthest from said plane 1111, converge theretoward at a greaterangle, terminate adjacent the transom of the boat, and are the widest attheir aft end.

The intermediatae pair of the separator devices is in length between thelengths of the other two pairs, they converge toward the plane ofsymmetry at an intermediate angle.

In other words, in the hull illustrated the pairs of separator devicesare located on opposite sides of the plane of symmetry progressivelygreater distances, fore to aft, they converge toward said plane atprogressively greater angles and the after ends of the forward pair ofseparators, overlap the forward ends of the intermediate pair ofseparators. Likewise, the after end of the intermediate pair overlap theforward end of the most rearward pair of separator devices. In otherhulls utilizing the invention this overlap of adjacent pairs ofseparators may not be necessary.

A common characteristic of all separators is that they all start withthe narrowest end near the chine 14, they progressively widen aftwardand they overlap each other. Only the aft pair of separators terminatesadjacent the transom of the boat in the design illustrated, but they maynot be the case in other designs at other specific loadings.

The function of the design and arrangement of these separators 12 is tocause flow separation at planing speed, the resulting cavity beingfilled principally by atmosphere. Flow separation of a fluid from asurface is promoted by any relatively abrupt or sharp interruption ofthe longitudinal continuity of the surface because of Newtons first lawof motion. The water flowing across the separator bottom surface tendsthus, on reaching the riser edge, to continue on a straight line,separating itself from the skin of the boat. The cavity occurringdownstream between the riser and adjacent boat bottom fills principallywith atmosphere. This flow separation reduces the area of wettedsurfaces, but more importantly it reduces the load induction effectconsequent upon flow along a relatively smooth and longitudinally convexsurface. Reduction of the load induction effect is equivalent toreducing the gross displacement materially, the performance is improvedrather dramatically both in speed and in the ability to carryexceptionally heavy payloads at speed.

This configuration gives the architect control in the arrangement of thehydrodynamic pressure distribution or pattern under the boats bottom.The exigencies of center of gravity location are thus much lessstringent, permitting a wider latitude in payload placement and allowingmuch larger engines to be placed in the extreme stern without destroyingthe boats inherent balance and stability.

Another important result of this configuration is the ability to operateetiiciently at a much lower trim than any comparable boat. This is dueto lower wetted area and reduced load induction effected by theseparator devices. Aside from the aesthetic value of a nearly level highspeed trim, the advantage of the lower trim lies in much softer ridingin choppy water, since, at this trim angle, the hull presents a mucheasier shape to the waves being traversed, and the aft seat passengershave a much better view ahead than is the case with most other types.

From the foregoing description, taken in connection with theaccompanying drawing, it is believed the teaching thereof will besufficient to enable one versed in the art to adapt the invention tohulls of differing form than that here illustrated, and to otherwiseutilize the basic concept of the invention.

I claim:

1. A hydroplane boat hull having stem, sides having lower edge portionsextending generally horizontally from stem to stern,

a transom stern, a defining a chine and a bottom, pairs of triangularlyshaped flow separator devices on said bottom on opposite sides of thelongitudinal plane of symmetry of said hull, said devices extending fromadjacent said chine aft, splayed in complementary relationship to saidplane of symmetry and converging aft, said pairs of devicesprogressively increasing in width aft in plan view.

2. The hull structure set forth in claim 1 wherein said pairs of devicesprogressively diminish in length aft.

3. The hull structure set forth in claim 1 wherein the most aft pair ofdevices is substantially greater in width in plan view than any otherpair.

4. The hull structure set forth in claim 1 wherein said pairs of devicesare spaced at progressively greater distances aft from said plane ofsymmetry.

5. The hull structure set forth in claim 1 wherein said devices aredisposed with one side substantially horizontal or normal to saidlongitudinal plane of symmetry.

6. The hull structure set forth in claim 1 wherein the outboard riseredges of said devices are relatively sharp and aftwardly converting.

7. The hull structure set forth in claim 1 wherein said bottom is ofconvex parabolic configuration.

8. The hull structure set forth in claim 7 wherein said bottom has asharp garboard region.

9. The hull structure set forth in claim 1, wherein the outboard riseredges of said devices at any transverse section are substantiallyparallel to said longitudinal plane of symmetry.

10. The hull structure set forth in claim 1, wherein the height of theriser edges of said devices falls within the following formula:

H=KA/B /V (non-dimensional) where:

H=Riser height A=Gross displacement (weight) of vessel B=Maximum breadthbetween chines V=Speed of advance K=Riser height coeflicient And, where:

H=Inches A=Pounds B=Inches V=KI101ZS Then: The value of K, for practicalhulls of this form, lies between 0.0660 and 0.8050, with the requirementin the case of relatively sharp (small radius) separator edges beingtoward the smaller value, and the requirement in the case oflarge-radius separator edges being toward the greater value.

References Cited UNITED STATES PATENTS 1,935,622 11/1933 Eddy 11466.52,039,586 5/1936 Eddy et al. 114-665- 2,423,860 7/ 1947 Van Patten114-66.5 3,117,544 1/1964 Schoell 114--66.5 3,315,284 4/1967 Ludlow 9--6ANDREW H. FARRELL, Primary Examiner.

